The present invention relates generally to facility management and control systems and, more particularly, to facility management and control systems and methods for use in the semiconductor wafer manufacturing industry to collect process data including particle measurement data from remote locations.
In order to monitor and control modern industrial processes, facility management and control systems have been developed. Facility management and control systems collect various types of process data. A facility management and control system can then analyze the process data for quality control purposes as described below.
The measurement instruments that provide the process data are typically distributed throughout the facility with the particular arrangement dependent upon the nature of the process being monitored and the configuration of the facility. In addition, various types of measurement instruments can be employed depending upon the process data that is to be collected. For example, measurement instruments are typically employed to measure process data such as temperatures, pressures, humidity levels, switch positions and the like. While these measurement instruments can operate independently, the process data provided by the measurement instruments that monitor a particular stage of a process are oftentimes collected by a programmable logic controller.
Although the measurement instruments are typically distributed at various locations throughout the facility depending upon the particular stage of the process that is to be monitored, facility management and control systems generally include a central computer for collecting and processing the data provided by the various measurement instruments. The central computer is typically located at a relatively centralized position, such as within a control room or the like. As such, the central computer is generally remote from most, if not all, of the measurement instruments by being positioned in a different room of the same building or in another building altogether. By collecting the data provided by the measurement instruments or, more commonly, by one or more programmable logic controllers with a central computer, the data can be more thoroughly analyzed such as by cross-checking or correlating the data obtained by measurement instruments that are designed to monitor different stages of the process.
The central computer can process the data in various manners for quality control and other purposes. In this regard, the data can be examined from a historical perspective in an attempt to determine, after the fact, the processing conditions that existed during the fabrication of products that were eventually determined to be of either unusually high quality or unacceptably low quality. In order to avoid fabricating a number of unacceptable products prior to detecting the problem and taking corrective action to bring the process back into tolerance, the central computer can compare the current process data to predetermined acceptable ranges of process data. As such, if the process data collected by the measurement instruments falls outside the predetermined range of acceptable process data, the central computer can trigger an alarm such that the process parameters can be quickly adjusted prior to fabricating a large number of unacceptable products.
One example of a process for which a facility management and control system has been developed is the wafer fabrication process. In this process, wafers, such as silicon wafers, undergo a number of different process steps in order to fabricate wafers having the desired characteristics, such as the desired resistivity, surface roughness, etc. A facilities management and control system that includes a central computer and a number of distributed measurement instruments is particularly useful for a wafer fabrication process since slight variations in the process parameters can substantially alter the characteristics of the resulting wafers, thereby causing wafers that will be unacceptable to be fabricated as a result of only minor changes in the process parameters. A facilities management and control system is also advantageous for a wafer fabrication process since the throughput of a wafer fabrication process is relatively high such that it is desirable to detect variations in the process parameters as soon as possible in order to reduce the number of unacceptable wafers that are fabricated.
In a wafer fabrication process, one of the most important process parameters is the particle count at different stages. In this regard, wafers are subjected to various environments during the fabrication process, some of which are designed to be ultrapure environments having relatively few particles or contaminants. For example, at different stages of the fabrication process, a wafer is typically washed with ultrapure water, exposed to ultrapure chemicals, subjected to high pressure gas, such as hydrogen or nitrogen, having relatively few particles or subjected to an aerosol having relatively few particles, such as within a cleanroom. During any of these stages of the fabrication process, it is desirable to measure the particles in the particular medium, such as the water, chemical, gas or aerosol. As such, various particle measurement instruments have been developed and are commercially available.
Unfortunately, these conventional particle measurement instruments are generally unable to transmit the data, such as the particle counts, that has been collected to a central computer that is remote from the particle measurement instruments in the same manner as other measurement instruments or programmable logic controllers. As such, dedicated computers were oftentimes co-located with the particle measurement instruments in order to collect and characterize the data. In order to correlate the data collected by the particle measurement instruments with the data collected by various other measurement instruments distributed throughout the wafer fabrication facility, technicians would have to manually collect the particle data from the dedicated computers associated with the respective particle measurement instruments distributed throughout the facility, such as by obtaining a printout of the particle data from each dedicated computer or downloading the particle data onto a computer diskette or the like. Typically, the particle data is then manually re-entered into a spreadsheet. By copying other process data from the facilities management and control system, i.e., the process data collected by other measurement instruments, and by exporting this other process data in spreadsheet format, this other process data can be merged with the particle data and the combined data set can be evaluated. As such, the various different types of data collected for the respective stages of the fabrication process can be correlated for training, quality control or other purposes.
As will be apparent, the manual collection and re-entry of the particle data can quickly become time consuming and is subject to errors during the manual re-entry process. As such, attempts have been made to connect the particle measurement instruments to a central computer by utilizing line drivers to transmit the particle data that is provided serially by the particle measurement instruments distributed about the facility to the central computer. Unfortunately, the line drivers are notoriously prone to the introduction of errors, particularly at the relatively high bit rates that would be utilized during the transmission of the particle data.
A facility monitoring system has been developed by Particle Measuring Systems, Inc. (PMS) of Boulder, Colorado that permits the particle data collected by PMS particle measurement instruments to be transmitted to a central computer via a computer network by using TCP/IP protocol. In addition to transmitting the particle data, the PMS particle measurement instruments generally include ports to which other measurement instruments can be connected. The PMS particle measurement instruments can therefore transmit the process data collected by these other measurement instruments along with the particle data to the central computer. For example, measurement instruments that can be connected to a PMS particle measurement instrument include a temperature sensor, a pressure gauge and the like.
Unfortunately, the PMS facility monitoring system does not interface with the measurement instruments of other vendors and therefore does not permit the process data collected by the measurement instruments of other vendors to be transmitted via the computer network for collection by the central computer. In addition, the central computer of a PMS facility monitoring system does not interface with measurement instruments designed to measure process data other than particle data unless these other measurement instruments are first connected to a PMS particle measurement instrument, and the process data collected by these other measuring instruments are transmitted along with the particle data by the PMS particle measurement instrument. Thus, the PMS facility monitoring system does not permit measurement instruments that are independent of the PMS particle measurement instruments to separately transmit process data, such as temperatures, pressures, humidity levels, switch positions or the like, via the computer network to the central computer for processing and correlation with the particle data provided by the PMS particle measurement instruments. As such, it would be desirable to provide a facilities management and control system and method that included a central computer that could universally communicate in a reliable manner with a variety of measurement instruments, including particle measurement instruments, without requiring manual intervention in order to collect and re-enter the particle data and without requiring all process data to be routed through the particle measurement instruments.
A universal system and method are therefore provided for collecting a plurality of different types of process data, including particle measurement data, from remote locations without requiring manual intervention. In this regard, the universal system includes a plurality of particle measurement instruments, such as aerosol particle monitoring instruments, liquid particle monitoring instruments and gas particle monitoring instruments, disposed at respective locations distributed about a facility in order to collect particle data. The universal system also includes a process data collection device for providing process data other than particle data, such as temperature, pressure, humidity level, switch position or the like. In addition, the universal system includes a central computer that is located remote from the plurality of particle measurement instruments and from the process data collection device and that is interconnected with the plurality of particle measurement instruments and the process data collection device by means of a computer network, such as a local area network and, more preferably, an Ethernet network. As such, the particle data collected by the respective particle measurement instruments and the other process data collected by the process data collection device can be transmitted across the computer network and received by the central computer that is located remote from the respective locations at which the process data is collected. According to the present invention, however, the process data collection device provides the particle data to the central computer in a manner that is independent of the plurality of particle measurement instruments, thereby greatly increasing the flexibility of the system and method. Thereafter, the particle data and the process data can be processed at the central computer.
According to the present invention, the universal system and method for collecting process data permit particle data to be collected at a variety of locations distributed about a facility and then transmitted to and processed by a central computer, typically in near real time, along with various other types of process data. Accordingly, the central computer can correlate the data received from different stages of the process in order to improve the quality control procedure for the respective process.
In order to transmit the particle data via the computer network to a remotely located central computer, the system of the present invention preferably includes a plurality of converters associated with respective particle measurement instruments. Each converter converts particle data that is provided by the respective particle measurement instrument according to a first protocol to a second protocol for transmission via the computer network to a central computer. Typically, the particle measurement instruments provide the particle data serially. As such, the plurality of converters generally convert the serial particle data to TCP/IP for transmission via the computer network to a remotely located central computer. Although the converter can be configured in various manners, the converter of one embodiment is a server such as a microserial server.
Typically, the process data collection device includes a programmable logic controller and a plurality of measurement instruments for collecting different types of process data and for providing the process data to the programmable logic controller. The programmable logic controller can, in turn, provide the process data to the central computer via the computer network in a manner that is independent of the plurality of particle measurement instruments. In this regard, the programmable logic controller as well as the measurement instruments associated therewith are independent of the particle measurement instruments and can therefore provide the process data that has been collected directly to the central computer via the computer network without first routing the process data through a particle measurement instrument.
According to one embodiment to the present invention, a computer program product is provided that processes a plurality of different types of process data collected from various locations distributed about a facility. The computer program product includes a computer readable storage medium, typically accessible by the central computer, that has computer readable program code means. The computer readable program code means includes first computer instruction means for receiving particle data via the computer network from any one of a plurality of particle measurement instruments located at respective remote locations. For example, the first computer instruction means typically receives particle data that is formatted in TCP/IP from any one of the plurality of particle measurement instruments. The computer readable program code means also include second computer instruction means for identifying the respective particle measurement instrument that provides the particle data. In embodiments in which at least one of the particle measurement instruments includes a plurality of measurement ports, the second computer instruction means also identifies the respective measurement port of the particle measurement instrument that provides the particle data. Further, the computer readable program code means includes third computer instruction means for processing the particle data based upon the respective particle measurement instrument identified as providing the particle data. As such, the third computer instruction means can include computer instruction means for generating an alarm that the particle data exceeds a predetermined threshold. In addition, the third computer instruction means can include computer instruction means for identifying trends in the particle data.
According to this embodiment to the present invention, the computer readable program code also includes fourth computer instruction means for separately receiving process data, other than particle data, via the computer network from a process data collection device and fifth computer instruction means for processing the process data. In one embodiment, the computer readable program code means also includes sixth computer instruction means for identifying the respective process data collection device that provides the process data received by the fourth computer instruction means such that the fifth computer instruction means processes the process data based upon the identity of the respective process data collection device.
Therefore, the system, method and computer program product of the present invention permit a plurality of different types of process data to be collected by a plurality of particle measurement instruments and other process data collection devices distributed at various locations about a facility and to then be formatted appropriately and transmitted via a computer network to a remotely located central computer for further processing. Accordingly, the central computer and, in particular, the computer program product operating thereon can collect the particle and other process data in real time or near real time in a manner that eliminates most sources of error such that the particle and other process data can be reliably analyzed for quality control purposes or the like. Thus, the system, method and computer program product of the present invention are particularly well suited for the collection and analysis of particle and other process data during a wafer fabrication process in order to identify process conditions that are out of tolerance prior to the fabrication of a substantial number of unacceptable wafers. By collecting the particle data at a central computer, the central computer and, in particular, the computer program product operating thereon can also correlate the particle data with other process data in a more efficient and reliable fashion in order to identify quality control issues or trends in the data that may need to be corrected.
The system, method and computer program product of the present invention also provides for process data other than the particle data to be provided in a manner that is independent of the particle measurement instruments. As such, the process data collection devices can be located remote from the particle measurement instruments and the process data collection devices can be supplied by different vendors than the particle measurement instruments. The system, method and computer program product of the present invention therefore collects a plurality of different types of process data in a manner that is flexible and that can be easily adapted to many different factory settings.